docs: def com_google_fonts_check_name_unwanted_chars(ttFont):
    """Substitute copyright, registered and trademark
       symbols in name table entries."""
    failed = False
    replacement_map = [("\u00a9", '(c)'),
                       ("\u00ae", '(r)'),
                       ("\u2122", '(tm)')]
    for name in ttFont['name'].names:
      string = str(name.string, encoding=name.getEncoding())
      for mark, ascii_repl in replacement_map:
        new_string = string.replace(mark, ascii_repl)
        if string != new_string:
          yield FAIL, ("NAMEID #{} contains symbol that should be"
                       " replaced by '{}'.").format(name.nameID,
                                                    ascii_repl)
          failed = True
    if not failed:
      yield PASS, ("No need to substitute copyright, registered and"
                   " trademark symbols in name table entries of this font.")